The present invention relates to a new and distinct cultivar of Physocarpus opulifolius and will be referred to hereafter by its cultivar name, ‘Donna May’. Physocarpus opulifolius is a deciduous shrub grown for landscape use. The primary objective of the Physocarpus opulifolius breeding program I initiated in St. Paul, Minn. was to develop a new Physocarpus opulifolius cultivar that possessed the purple foliage color of Physocarpus opulifolius ‘Monlo’ (disclosed in U.S. Plant Pat. No. 11,211) and the compact, well-branched growth habit and small foliage of Physocarpus opulifolius var. nanus (not patented).
‘Donna May’ originated by crossing an unnamed Physocarpus opulifolius seedling (code designation of this seeding is 2001-1) as the female parent and an unknown plant of Physocarpus opulifolius var. nanus as the male parent. 2001-1 originated from a cross I made between Physocarpus opulifolius ‘Monlo’ (disclosed in U.S. Plant Pat. No. 11,211) as the female parent and an unknown plant of Physocarpus opulifolius var. nanus as the male parent. 2001-1 has purple foliage and a growth habit and foliage size intermediate to its parents. The pollination that led to the population of progeny that ‘Donna May’ was identified within occurred in June 2004. The seeds of this population germinated during the winter of 2004/2005 indoors under florescent lights. Seedlings were transplanted to an outdoor garden bed in St. Paul, Minn. in spring of 2005 and ‘Donna May’ was selected as a single plant from the population of progeny during the summer of 2005. ‘Donna May’ was first asexually propagated using semi-hardwood cuttings in the fall of 2005. I have found that the characteristics of ‘Donna May’ are stable and true to type over successive generations of vegetative propagation.
‘Donna May’ was unique from all other Physocarpus seedlings because of its dark purple foliage color, very compact, well-branched plant habit, and small foliage. These traits led to it being chosen as an advanced selection in the summer of 2005 and asexually propagated for the first time in the fall of 2005. When ‘Donna May’ first flowered in 2006 it was discovered that ‘Donna May’ also possesses attractive flowers with pink petals that contrast nicely with the foliage.